You are looking for a firm, symmetrical watermelon that is free from bruises, cuts or dents. The watermelon should be heavy for it’s size. Watermelon is 92% water, most of the weight is water. The underside of the watermelon should have a creamy yellow spot from where it sat on the ground and ripened in the sun.
If you want to be super technical, the real term is octothorpe. In terms of etymology, the ”octo-“ refers to “eight,” which is in reference to the points on the symbol. However, where “-thorpe” stems from is still up for debate. Some believe it was named after Olympian Jim Thorpe. Others do not agree and argue that it was just a random suffix.